Commit c1fdb68e authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
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USB: EHCI: changes related to qh_refresh() 



This patch (as1638) makes several changes to the ehci-hcd driver, all
related to the qh_refresh() function.  This function must be called
whenever an idle QH gets linked back into either the async or the
periodic schedule.

	Change a BUG_ON() in the qh_update routine to a WARN_ON().
	Since this code runs in atomic context, a BUG_ON() would
	immediately freeze the whole system.

	Remove two unneeded calls to qh_refresh(), one when a QH is
	initialized and one when a QH becomes idle.  Adjust the
	adjacent comments accordingly.

	Move the qh_refresh() and qh_link_periodic() calls for new
	interrupt URBs to after the new TDs have been added.

	As a result of the previous two changes, qh_refresh() is never
	called when the qtd_list is empty.  The corresponding check in
	qh_refresh() can be removed, along with an indentation level.

These changes should not cause any alteration of behavior.

Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c79041a4

drivers/usb/host/ehci-q.c

+20 −32
Original line number Diff line number Diff line
@@ -90,7 +90,7 @@ qh_update (struct ehci_hcd *ehci, struct ehci_qh *qh, struct ehci_qtd *qtd) 
	struct ehci_qh_hw *hw = qh->hw;



	/* writes to an active overlay are unsafe */

	BUG_ON(qh->qh_state != QH_STATE_IDLE);

	WARN_ON(qh->qh_state != QH_STATE_IDLE);



	hw->hw_qtd_next = QTD_NEXT(ehci, qtd->qtd_dma);

	hw->hw_alt_next = EHCI_LIST_END(ehci);
@@ -123,11 +123,8 @@ qh_refresh (struct ehci_hcd *ehci, struct ehci_qh *qh) 
{

	struct ehci_qtd *qtd;



	if (list_empty (&qh->qtd_list))

		qtd = qh->dummy;

	else {

		qtd = list_entry (qh->qtd_list.next,

				struct ehci_qtd, qtd_list);

	qtd = list_entry(qh->qtd_list.next, struct ehci_qtd, qtd_list);



	/*

	 * first qtd may already be partially processed.

	 * If we come here during unlink, the QH overlay region
@@ -135,13 +132,9 @@ qh_refresh (struct ehci_hcd *ehci, struct ehci_qh *qh) 
	 * qtd is updated in qh_completions(). Update the QH

	 * overlay here.

	 */

		if (qh->hw->hw_token & ACTIVE_BIT(ehci)) {

	if (qh->hw->hw_token & ACTIVE_BIT(ehci))

		qh->hw->hw_qtd_next = qtd->hw_next;

			qtd = NULL;

		}

	}



	if (qtd)

	else

		qh_update(ehci, qh, qtd);

}
@@ -553,12 +546,9 @@ qh_completions (struct ehci_hcd *ehci, struct ehci_qh *qh) 
	 * overlaying the dummy qtd (which reduces DMA chatter).

	 */

	if (stopped != 0 || hw->hw_qtd_next == EHCI_LIST_END(ehci)) {

		switch (state) {

		case QH_STATE_IDLE:

			qh_refresh(ehci, qh);

			break;

		case QH_STATE_LINKED:

			/* We won't refresh a QH that's linked (after the HC

		if (state == QH_STATE_LINKED) {

			/*

			 * We won't refresh a QH that's linked (after the HC

			 * stopped the queue).  That avoids a race:

			 *  - HC reads first part of QH;

			 *  - CPU updates that first part and the token;
@@ -568,13 +558,12 @@ qh_completions (struct ehci_hcd *ehci, struct ehci_qh *qh) 
			 *

			 * That should be rare for interrupt transfers,

			 * except maybe high bandwidth ...

			 *

			 * Therefore tell the caller to start an unlink.

			 */



			/* Tell the caller to start an unlink */

			qh->needs_rescan = 1;

			break;

		/* otherwise, unlink already started */

		}

		/* otherwise, unlink already started */

	}



	return count;
@@ -957,14 +946,13 @@ done: 


	/* NOTE:  if (PIPE_INTERRUPT) { scheduler sets s-mask } */



	/* init as live, toggle clear, advance to dummy */

	/* init as live, toggle clear */

	qh->qh_state = QH_STATE_IDLE;

	hw = qh->hw;

	hw->hw_info1 = cpu_to_hc32(ehci, info1);

	hw->hw_info2 = cpu_to_hc32(ehci, info2);

	qh->is_out = !is_input;

	usb_settoggle (urb->dev, usb_pipeendpoint (urb->pipe), !is_input, 1);

	qh_refresh (ehci, qh);

	return qh;

}

drivers/usb/host/ehci-sched.c

+6 −3
Original line number Diff line number Diff line
@@ -792,7 +792,6 @@ static int qh_schedule(struct ehci_hcd *ehci, struct ehci_qh *qh) 
	unsigned	frame;		/* 0..(qh->period - 1), or NO_FRAME */

	struct ehci_qh_hw	*hw = qh->hw;



	qh_refresh(ehci, qh);

	hw->hw_next = EHCI_LIST_END(ehci);

	frame = qh->start;
@@ -844,8 +843,6 @@ static int qh_schedule(struct ehci_hcd *ehci, struct ehci_qh *qh) 
	} else

		ehci_dbg (ehci, "reused qh %p schedule\n", qh);



	/* stuff into the periodic schedule */

	qh_link_periodic(ehci, qh);

done:

	return status;

}
@@ -891,6 +888,12 @@ static int intr_submit ( 
	qh = qh_append_tds(ehci, urb, qtd_list, epnum, &urb->ep->hcpriv);

	BUG_ON (qh == NULL);



	/* stuff into the periodic schedule */

	if (qh->qh_state == QH_STATE_IDLE) {

		qh_refresh(ehci, qh);

		qh_link_periodic(ehci, qh);

	}



	/* ... update usbfs periodic stats */

	ehci_to_hcd(ehci)->self.bandwidth_int_reqs++;

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